FOR 21 years, Vicki Arnold's family has been told the mild-mannered chartered accountant bashed her best friend with a rock, slit her throat and shot her twice before turning the gun on herself - firing two shots through her own head in an apparent murder-suicide.

She did this, according to a police investigation and two coronial inquests, despite having no motive and no history of depression or any other mental health issues.

Yesterday, State Coroner Michael Barnes tore holes in the findings of police and the previous inquests - declaring it was more likely Ms Arnold, 27, and her best friend Julie-Anne Leahy, 26, were murdered.

In an extraordinary hearing before a packed courtroom, Mr Barnes ordered Mrs Leahy's husband Alan stand trial on two counts of murder.

A warrant was issued for his arrest and he is expected to be extradited from Western Australia to face court in Queensland.

Mr Leahy yesterday told The Courier-Mail he would maintain his innocence.

The bodies of the women were found inside the Leahy family 4WD in remote bushland near Cairns in August 1991 - two weeks after they failed to return from a late-night fishing trip.

"Those involved in the early stages of the investigation failed to gather, lost or corrupted evidence that may have established the truth of what happened at Cherry Tree Creek on the night of July 26, 1991," Mr Barnes said.

"They then set about squeezing what evidence was left into an explanation that required no further action."

He said two coronial inquests went along with the police opinion that the women's deaths were an open-shut murder-suicide.

The court heard Mrs Leahy's husband told police the women had left home after midnight to go fishing and never returned.

Mr Barnes said it was telling that Mr Leahy spent that night in bed with his wife's 16-year-old sister Vanessa.

"Alan Leahy spent considerable time in his wife's sister's bed on the night the two women disappeared," he said.

"A possible interpretation for what would seem cavalier behaviour is that he knew his wife would not be returning."

Mr Barnes also found:

While Ms Arnold had bought the gun that was used to shoot the women, the most likely scenario was that she had done so for someone else. Mr Barnes said she knew nothing about guns, yet insisted on buying a .22 rifle while giving various explanations as to why she needed it.

Ms Arnold had neither the equipment or the know-how to saw down a rifle. Mr Leahy did and lied about owning a vice, which would have been used to shorten the barrel.

Ms Arnold had no motive, appeared content the night she disappeared and had apparently embarked on a midnight fishing trip despite having made work appointments for 6am the following day.

It was unlikely Ms Arnold had shot herself in the back of the head after first shooting herself in the thigh and chin.

Trajectory examinations found one bullet was likely fired from the back seat.

The sawn-off barrel from the gun, a hacksaw and instruction manual were placed inside a pillow slip from the Leahy house and left in Ms Arnold's driveway two weeks after her body was found. Mr Barnes said "only someone who had themselves been involved in the deaths had a motive to do that".

SHOT DEAD: Best friends Vicki Arnold and Julie-Anne Leahy

He said while Ms Arnold did not appear to have a motive, Mr Leahy did.

The court heard Mr Leahy had been having an affair with his sister-in-law, had mounting debts and stood to gain $120,000 from his wife's life insurance. He also lied about owning true crime magazines - one depicting a murder made to look like a murder-suicide. The court heard the day before the women disappeared, Mrs Leahy had asked her younger sister to stay home from school - a request the teenager was convinced meant Mrs Leahy wanted to confront her about the affair.

Mr Barnes ordered Mr Leahy to stand trial at the next sittings of the Supreme Court in Cairns, giving him 14 days to surrender to police.

The women's relatives in court - and others viewing the hearing live in Cairns - cried and applauded as Mr Barnes delivered his finding.

Mrs Leahy's brother Peter Martin punched the air.

LONG BLAMED: Vicki Arnold at work in her Hall Chadwick office. Picture: Aaron Francis

"I'm on top of the world," he said. "(The decision) takes Vicki straight out of the picture - as it should have been from word go. We can wake up tomorrow morning and have a smile on our face."

"I've waited nearly 22 years for this result," she said. "I've lost a lot of sleep over the years. Who knows if I'll get any sleep tonight." She thanked Mr Barnes, her lawyer Philip Bovey and State MP Curtis Pitt for correcting a "miscarriage of justice".

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THE EVIDENCE

The crime scene

Mrs Leahy's throat was slashed, her body held upright in the driver's seat by a seat belt wrapped around her neck. She had been bashed with a rock and shot twice in the head. Ms Arnold's body was slumped on the passenger-side floor with bullet wounds to her thigh, jaw and behind the right ear, her hand resting on the stock of a sawn-off rifle with a shell in the breech.

State Coroner Michael Barnes said he doubted the gun would have come to rest in such a manner.

The assumption

Within four hours, police declared the incident a murder-suicide. The crime scene was cleared and the 4WD towed to Yungaburra, where it was stored inappropriately and the elements tainted any forensic evidence.

The gun

The gun's barrel and the hacksaw used to cut it down were discovered in Ms Arnold's garage two weeks after the women were found dead. Two police officers, Bill Hendrikse and Sgt Bernie Wilce, swore in the witness box the pillow case containing the parts was not there during an initial search of the unit. Ms Arnold's former neighbour, Pamela Fox, said she found the gun parts in the garage the day after she saw someone running from the home during the night.

The magazines

Mr Leahy gave police a series of murder-themed magazines after the women's deaths. He told officers Ms Arnold borrowed them from the Leahy household. But he told the inquest he did not remember the magazines belonging to the family - despite most of them having the name "Leahy" scrawled on the inside cover.

The sister

During the hearing Mrs Leahy's teenage sister, Vanessa, gave evidence that she was in a sexual relationship with Mr Leahy and was terrified her sister would find out.

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MURDER MYSTERY AT CHERRY TREE CREEK

How the events unfolded

July 26, 1991: Julie-Anne Leahy, 26, and Vicki Arnold, 27, are reported missing after Mrs Leahy's husband, Alan, says they failed to return from a fishing trip to Lake Tinaroo.

August 9, 1991: Trailbike riders find the women's bodies about 5pm in the the Leahy family's Nissan Patrol, about 15km out of Atherton on a bush track. Despite the bizarre scene, police rule their deaths a murder-suicide and the vehicle and bodies are hastily removed.

July 30, 1992: First inquest into the women's deaths begins at Atherton Coroner's Court. After hearing the evidence, Coroner Hamilton Spicer supports the murder-suicide theory.

May, 1998: The Mengler and O'Gorman report is highly critical of the original police investigation.

April 19, 1999: A second inquest into the women's deaths begins. The Coroner's Court hears of Ms Leahy's younger sister Vanessa's affair with her husband. A forensic expert tells the court it would be highly unlikely a person would shoot themself in the head twice.

February 21, 2000: Coroner Gary Casey rules again in favour of the murder-suicide theory. The Arnold and Leahy families are stunned.

September, 2005: Former Far North detective Bill Hendrikse, one of the first officers at the scene, claims a senior police officer refused to order an investigation into the suspected double murder because of overtime costs.

July, 2008: Homicide detectives investigate whether the women were killed because they knew too much about a bungled bank robbery after a witness comes forward with fresh evidence.

October 23, 2010: Attorney-general Cameron Dick announces a third inquest will be held after lobbying from Mulgrave MP Curtis Pitt - Bill Hendrikse's nephew.

November 14, 2011: Third inquest begins before State Coroner Michael Barnes and hears evidence shedding doubt on the adequacy of the initial police investigation, and some expert witnesses say they lean more towards a double-murder scenario.

March 1, 2013: Mr Barnes hands down his findings and commits Alan Leahy to stand trial for murder.

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